A commercially available dietary supplement sold as Advantra Z® contains the protoalkaloids synephrine, tyramine, N-methyltyramine, hordenine and octopamine, with synephrine being the main ingredient. The makers of Advantra Z® claim that the composition shows lipolytic and thermogenic activity and increases resting metabolic rate (RMR) in humans, with synephrine and octopamine appearing to be particularly effective in this regard. Such properties have value in treatment of weight loss and in improving both physical performance and overall fitness.
The flavonoids hesperitin and naringenin are found in citrus fruits and juices as their glycosides, hesperidinand naringin, respectively. Hesperidin is present predominantly in the peels of lemons and oranges as well as in a wide variety of other citrus species, while naringin is mainly found in the peels of grapefruit. Both flavonoids are commercially readily available in the form of powders, tablets, capsules and the like. The sugar moieties for rutinose (rhamnose and glucose) of these flavonoids must be cleaved to enable the flavonoids to be absorbed; typically this cleavage occurs naturally in the GI tract of a human or mammal. Experiments involving human subjects, animals and cell culture systems have shown that naringin and hesperidin exhibit a wide range of potentially beneficial physiological and biochemical effects. However, no studies have been conducted on the effects of either flavonoid on metabolic rate, blood pressure or heart rate.